The present invention relates to a closure for a container, such as an envelope, box, or carton, and the process of constructing the closure. More specifically, the invention pertains to a closure employing a preapplied adhesive covered by a removable protective liner.
Many types of containers, such as envelopes and boxes, are sealed with adhesive closures. For convenience, the adhesive is usually preapplied to either a movable flap, or the body of the container where the flap contacts, eliminating the need for tape or glue. Typically, such preapplied adhesive is protected from inadvertent contact by a protective liner covering the adhesive.
Johnson et al. U.S. Pat. No. 3,372,861 discloses an adhesive strip on an envelope flap which is covered by a protective liner. The protective liner extends beyond the edge of the flap enabling it to be easily removed. This type of closure typically requires a two-step manufacturing process of: (1) applying the adhesive to the flap; and (2) covering the adhesive with the protective liner.
Adhesive transfer tape, sometimes referred to as "glue tape," can convert this two-step manufacturing process to a single step. However, this benefit is achieved at the cost of complicating the removal of the protective liner. If the glue tape is applied extending beyond the edge of the flap, the exposed adhesive on the extended portion of the glue tape would transfer to anything with which it came in contact. Alternatively, if the glue tape is applied to a flap entirely within the flap's margins, the protective liner lacks an extended free margin to grasp--since glue tape typically has adhesive applied to the surface area of one side of the tape. To peel the protective liner from the adhesive, one of its corners must be pried up with a thin object, such as a fingernail.
What is needed then, is an improved adhesive flap closure, and a method of making the same, which may be constructed by a single-step application of both adhesive and a protective liner while providing for easy removal of the protective liner.